Daily Security Briefing #277

June 6, 2026 | Read Online

GRIDTIDE disrupted, AI narratives shift, and SolarWinds Serv-U vulnerabilities exposed…

Executive Summary

Cybersecurity threats continue to evolve with malicious actors adapting to disruptions. The recent GRIDTIDE campaign disruption highlights collaborative efforts between industry partners. Meanwhile, critical vulnerabilities in SolarWinds Serv-U have been exposed, and a new Lockdown Mode has been introduced for ChatGPT. Additionally, AI narratives are shifting as the tech moves at an unprecedented pace.

Top Articles

Malspam Campaign Abuses DoubleClick to Deploy Stealthy .NET Loader A sophisticated malspam campaign is actively exploiting Google’s DoubleClick ad-tracking infrastructure to bypass enterprise email security gateways. Discovered by researchers at Huntress, the attack utilizes highly personalized dynamic lures to initiate a complex, five-stage infection chain that actively dismantles local defenses before deploying process-hollowed payloads. GBHackers

China-Linked Espionage Cluster Deploys Custom ASPX/ASHX Shells on IIS A previously disclosed China-linked threat cluster, tracked as OP-512, has been observed deploying a purpose-built web shell framework to compromise Internet Information Services (IIS) servers. Identified by ReliaQuest, the espionage operation targeted a Windows Server 2016 environment running an end-of-life .NET Framework 4.0. GBHackers

CISA Warns of Exploited SolarWinds Serv-U Vulnerability The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has added CVE-2026-28318 to its Known Exploited Vulnerabilities (KEV) catalog after confirming that threat actors are actively targeting a high-severity flaw in SolarWinds Serv-U to remotely crash file transfer servers without requiring authentication. CyberPress

New ChatGPT Lockdown Mode Limits Tools That Could Enable Data Exfiltration OpenAI has begun rolling out a new Lockdown Mode to ChatGPT for eligible personal accounts to reduce the risk of data exfiltration arising from prompt injection attacks. The feature is primarily designed for people and organizations that handle sensitive data and require stricter protection guarantees. The Hacker News

Critical Everest Forms Pro flaw exploited to take over WordPress sites Hackers are actively exploiting a critical vulnerability (CVE-2026-3300) in the Everest Forms Pro plugin, which lets them take complete control of a WordPress website. BleepingComputer

Suspicious Polyfill login prompts pop up on Toshiba, Muji websites Tech giant Toshiba and mega-retailer Muji warned visitors that suspicious sign-in screens popping up on their websites could collect credentials. BleepingComputer

AI Transparency: This newsletter uses AI to curate, rank, and summarize cybersecurity content from leading industry blogs. All articles link directly to original authors. Executive summaries are AI-generated based on article content. I curate the sources and deliver the digest—the original authors deserve the credit for their excellent work.